1. Field of the Invention
The present invention relates to an antenna capable of micro tuning and macro tuning for a wireless terminal, and more particularly, to an antenna capable of micro tuning and macro tuning for a wireless terminal, which is capable of control in a dual service band having a difference of a certain or higher frequency, and which is capable of frequency tuning between channels in each service band.
2. Description of the Related Art
As wireless communication has been developed, wireless network can be accessed by wireless terminals, such as personal computers, notebooks, mobile phones, PDA and so on. The technology for supporting the wireless access to network in real time in mobile working environment is called wireless local-area network (WLAN).
According to the WLAN standards of IEEE 802.11, in IEEE 802.11b, wireless signals are transmitted and received through the 2.4 GHz frequency band which is the industrial, scientific and medical (ISM) band, and in IEEE 802.11a, wireless signals are transmitted and received through the 5 GHz frequency band which is the unlicensed national information infrastructure (UNII) band.
In the 2.4 GHz, which is the frequency band for IEEE 802.11b, transmission at the bandwidth of 83.5 MHz, from 2.4 GHz to 2.4835 GHz, is permitted. In the 5 GHz, which is the frequency band for IEEE 802.11a, transmission at the bandwidth of a total of 300 MHz, from 5.15 GHz to 5.35 GHz and from 5.725 GHz to 5.825 GHz, is permitted.
The WLAN service has a different frequency band according to the standards utilized. Consequently, the standards may change at any time or in different localities. In this case, since an existing wireless terminal is manufactured so as to process signals within the frequency band according to one standard only, a user may need to purchase another terminal for a new standard. To prevent such waste, a wireless terminal which functions in different standards needs to be developed.
In order to operate a wireless terminal in the frequency bands of both standards, an antenna has to operate in both frequency bands. For this purpose, a wireless terminal is provided with an antenna operating in both frequency bands. That is, an antenna having a very broad frequency band may be installed to operate in the frequency band of 2.4 GHz to 5 GHz, or an antenna having a dual frequency band may be installed to separately operate in the frequency band of 2.4 GHz and in the frequency band of 5 GHz.
However, when using the antenna operating in the very broad frequency band of 2.4 GHz to 5 GHz, noise and interference occur in a non-use band.
Due to the aforementioned problem, antenna developing industries have developed an antenna separately operating in each of the 2.4˜2.5 GHz and 4.9˜5.9 GHz frequencies. However, this antenna has not yet been sufficiently small in size. When using the antenna separately operating in the both frequency bands, tuning performance between channels in each frequency band is not taken into consideration.